BCECE Engineering BCECE Engineering Solved Paper-2008

  • question_answer
    If \[x=\sqrt{\frac{2+\sqrt{3}}{2-\sqrt{3}},}\]then \[{{x}^{2}}{{(x-4)}^{2}}\] is equal to

    A)  7                            

    B)         4                            

    C)  2                            

    D)         1

    Correct Answer: D

    Solution :

    Since,\[x=\sqrt{\frac{2+\sqrt{3}}{2-\sqrt{3}}}=\sqrt{\frac{(2+\sqrt{3})(2+\sqrt{3})}{(2-\sqrt{3})(2+\sqrt{3})}}\] \[=\frac{2+\sqrt{3}}{\sqrt{4-3}}=2+\sqrt{3}\] \[\therefore \]  \[{{x}^{2}}{{(x-4)}^{2}}={{(2+\sqrt{3})}^{2}}{{(2+\sqrt{3}-4)}^{2}}\]                 \[={{(\sqrt{3}+2)}^{2}}{{(\sqrt{3}-2)}^{2}}\]                 \[={{[(\sqrt{3})]}^{2}}-{{(2)}^{2}}{{]}^{2}}\]                 \[={{(3-4)}^{2}}={{(-1)}^{2}}\] \[=1\]


You need to login to perform this action.
You will be redirected in 3 sec spinner